Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
H,W = map(int, input().split())
List = []
queue = [(0,0,1)]
shape = 0
used ={(0,0)}
for i in range(H):
    x = input()
    shape += x.count('#')
    List.append(x)

def check(x,y,c):
    if(x>W-1 or y>H-1 or x<0 or y<0):
        return
    if(List[y][x] == '#'):
        return
    if(x,y) in used:
        return
    queue.append((x,y,c+1))
    used.add((x,y))

flag = -1
while(len(queue) != 0):
    x,y,c = queue[0]
    if x==W-1 and y==H-1:
        flag = 1
        break
    queue.pop(0)
    check(x+1,y,c)
    check(x, y+1,c)
    check(x-1,y,c)
    check(x, y-1,c)
if(flag == 1):
    print(H*W - c - shape)
else:
    print(-1)